CEMS- Untersuchungen an Grenzflächen in antiferromagnetisch koppelnden Schichtsystemen

Landes, J.

Book/Report

FZJ-2018-03523

CEMS- Untersuchungen an Grenzflächen in antiferromagnetisch koppelnden Schichtsystemen

Landes, J. (Corresponding author)FZJ*

1991
Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag Jülich

Jülich : Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag, Berichte des Forschungszentrums Jülich 2489, 98 p. (1991)

Please use a persistent id in citations: http://hdl.handle.net/2128/18915

Report No.: Juel-2489

Abstract: In this thesis interface effects in antiferromagnetic coupling films were investigated. In the first part the $^{57}$Fe Conversion Electron Mössbauer Spectroscopy (CEMS) method was used to analyze films of the structure Fe/X (X=Cr,Gd,Y), i. e. with only one interface. The second part describes measurements of the technically important system X/Fe/X. The distance dependence of the magnetic hyperfine fields near the interfaces in epitaxial Fe/Cr and partly epitaxial Fe/Gd and Fe/Y bilayers were measured using the $^{57}$-CEMS method. It was found that the Fe-Cr magnetic interaction extends only up to the second Fe-neighbour at the Fe/Cr interface, whereas the interaction range at the Fe/Gd interface is four times larger. The Fe/Y system behaves very similar to the free Fe-surface. The results for the Fe/Cr system are in good agreement with LMTO band structure calculations. The Néel temperature of a thin Cr interlayer in a. Fe/Cr/Fe sandwich structure was determined in dependence of the Cr layer thickness. In the second part of the thesis the film growth of Gd/Fe and Y/Fe layered structures was investigated by means of $^{57}$Fe-CEMS measurements and High Resolution Transmission Electron Microscopy (HRTEM). The Fe-layer grows on the Gd (Y) sublayer in an amorphous structure up to a critical thickness of d$_{c}$ = 2.3 ± 0.1 nm. On further increasing the Fe-thickness a rapid transformation to a nanocrystalline structure throughout the total Fe-layer occurs. The origin of this effect is suggested to be due mainly to the extreme misfit between the structural parameters of Fe and Gd (Y). The magnetism can be related to the structure of the films. Nanocrystalline Fe/Gd samples show a ferrimagnetic coupling with a compensation temperature of the sublattice magnetizations ("Giant Ferrimagnet"). In films with amorphous Fe such a compensation point could not be observed.

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